In a broadcasting station, broadcast program data, for example commercials(CM) programs, etc. is usually stored in a library. The necessary broadcast program data is successively selected, reproduced, and transmitted from that library according to a broadcast schedule. This series of processing is controlled and managed by a control means called a library management system (LMS). Using this LMS, a library having data on an enormous number of CM programs recorded in a very large number of recording media, for example, several thousand video cassette tapes, is managed and suitably used for broadcasting CM programs.
However, usually, in a broadcasting station, to prevent any interruption of the broadcast, the system is configured so that important apparatuses such as said library are duplicated, and even if one breaks down, operation by the other is possible. However, such duplex provisions require double the cost. In particular, duplication of large scale apparatus such as said library for CM programs has a great economic influence.
Further, in such a multiplexed library system, it is necessary to select one series of data for actual broadcasting from the plurality of broadcast program data output. Normally, this selection is performed by the switching operator viewing the monitor to check the quality of the video and audio at the main switcher, but this work places a heavy burden on the switching operator.